Association of Psoriatic Disease With Uveitis: A Danish Nationwide Cohort Study

IMPORTANCE: Psoriasis, psoriatic arthritis, and uveitis are inflammatory disorders with significant overlap in their inflammatory pathways. Limited evidence is available about the relationship between psoriatic disease and uveitis. OBJECTIVE: To investigate the potential bidirectional relationship between psoriatic disease, including psoriasis and psoriatic arthritis, and uveitis. DESIGN, SETTING, AND PARTICIPANTS: We performed a nationwide cohort study of the Danish population from January 1, 1997, through December 31, 2011. We included 74 129 Danish patients with psoriasis who were 18 years or older during the study period. Patients were identified through administrative registries, and information on age, sex, socioeconomic status, medication, and comorbidity was obtained using individual-level linkage of administrative registers. We performed data analysis from January 27 through March 4, 2015. EXPOSURES: Diagnosis of mild or severe psoriasis or psoriatic arthritis for uveitis risk and diagnosis of uveitis for the risk for psoriasis or psoriatic arthritis. MAIN OUTCOMES AND MEASURES: Diagnosis of uveitis, mild psoriasis, severe psoriasis, or psoriatic arthritis. We calculated incidence rates (IRs) and estimated IR ratios adjusted for potential confounders using Poisson regression. RESULTS: We identified 74 129 cases of psoriasis and psoriatic arthritis and 13 114 cases of uveitis. The IRs (95% CIs) for uveitis were 2.02 (1.99-2.06), 2.88 (2.33-3.56), 4.23 (2.40-7.45), and 5.49 (3.36-8.96) for the reference population and those with mild psoriasis, severe psoriasis, and psoriatic arthritis, respectively. In the reference population, these IRs (95% CIs) were 9.37 (9.30-9.45), 1.12 (1.10-1.15), and 1.04 (1.01-1.06), and in patients with uveitis, these statistics were 15.51 (12.92-18.62), 2.66 (1.72-4.13), and 4.25 (3.00-6.01) for mild psoriasis, severe psoriasis, and psoriatic arthritis, respectively. Adjusted IR ratios (95% CIs) for uveitis were 1.38 (1.11-1.70 [P = .02]), 1.40 (0.70-2.81 [P = .34]), and 2.50 (1.53-4.08 [P